Some applications and environments can present tremendous challenges for lighting systems. For example, the lighting systems used in tents and portable shelters, e.g., as may be used in military applications, disaster relief applications, and emergency applications, as well as used in fixed structures such as refineries, mines and other industrial, residential and commercial applications, are often exposed to extreme conditions. Conventionally, such lighting systems have relied upon incandescent or fluorescent bulbs, both of which are relatively fragile, and which as a result often require bulky housings to protect the bulbs from breakage. Also, due to the temporary nature of such shelters, the lighting systems are often left exposed and subject to being inadvertently bumped by personnel or equipment, increasing the risk of breakage. Lighting systems may also be exposed to harsh operating conditions, which for fluorescent-based approaches can lead to poor light output, e.g., in cases of extreme cold.
In addition, due to the bulkiness and fragility of conventional lighting systems, the systems are often installed in a facility only after the facility has been constructed, and must be removed before the facility can be broken down for stowage or transport. Particularly in large facility or shelter complexes, where tens or hundreds of rapidly deployable shelters need to be constructed in a short period of time, the additional labor required to install and tear down the lighting systems can be excessively burdensome.
Energy consumption is also a significant concern for many lighting systems. Incandescent bulbs are extremely inefficient, leading to excessive energy costs, power consumption, and heat generation, the latter of which may require special accommodations to reduce the risk of fire.
In addition, in some military applications, it may be desirable to provide “blackout” capability in a lighting system for the protection of military personnel in battlefield environments. Conventionally, when blackout conditions are required, military personnel are typically required to place a color filter over each light fixture to filter out infrared radiation. In some fluorescent fixtures, for example, retractable filter screens are built into the housings, so that military personnel can manually slide the filter screens over the fluorescent bulbs when blackout conditions are required. In an installation of hundreds or thousands of individual fixtures in a facility or complex, however, the time and effort required to convert all fixtures to a blackout condition can be excessively long, potentially increasing the danger to military personnel health and well being.
One technology that is increasingly being used in lighting systems is solid state Light Emitting Diode (LED)-based lighting. LED lights tend to be more durable and longer lasting than incandescent and fluorescent lights, and the efficiency continues to increase to the point that current LED lights are comparable to fluorescent lights, and are continuing to improve.
Solid state lighting systems, however, are also subject to numerous drawbacks and challenges. For example, heat dissipation is currently a significant problem for LED light fixtures. The LED's used in lighting fixtures are often packaged with integrated heat sinks, and the packages are typically mounted on a circuit board. A larger, more efficient cooling system, e.g., using a larger heat sink and/or other cooling components, is then mounted to the opposite side of the circuit board, so that the generated heat is dissipated through the circuit board. While metallic through holes may be used to improve the dissipation of heat through the circuit board, however, the conduction of heat through the circuit board remains a problem with respect to fixture reliability. Another drawback of LED lights is the directed nature of the light generated by the LED's. It is desirable in many lighting environments for the light to be evenly dispersed and consistent throughout a lit area. Conventional LED light fixtures, however, often generate (hot) bright spots and subsequently dark spots within illuminated areas.
Therefore, a significant need continues to exist in the art for a solid state lighting system that overcomes the aforementioned drawbacks of conventional lighting systems.